Adjusting device for grinding-wheels.



WI. MAAG Amusme DEVICE FoRfGmNolNG WHEELS.

APPLICATION FILED JULY 26,1916.

Patented June 5, 191'?.

4 SHEETS-SHEET 1.

IVI. IVIAG.

ADJUSTING DEVICE FOR GRINDING WHEELS.

APPLICATION FILED IULY 26,19I6.

Patented J une 5, 1917.

4 SHEETS-SHEET 2.

I a 19 L90 I II IIIM IIILMIIIIIIIIIIIIIIIII IIE:

M. MAAS.

Amusm DEvxce PoR Gmmnme WHEELS.

APPLICATION FILED IULY 25,196.

Patented June 5, 1917.

4 SHEETS-SHEET 3- lll lllllli] vl Illlll lili M. MAAG.

ADJUSTING DEVICE FOR GRINDING WHEELS.

APPLICATIONFILED 1uLY2e,191e.

` Patented June 5 1917 4 SHEETS-SHEET 4.

union.,

MAX TAAGl, ZEICH, SWITZERLAND.

ADJUSTING DEVICE FOR @BINDING-WHEELS.

Specification of Letters Patent.

Patented J une 5, 1,91*?,

application sied July as, 191e. semi nannies.

To all whom t may concern:

Be it known that l, MAX Mano, a citizen of the Republic of Switzerland,residing at i Hardstrasse 219, Zurich, Switzerland, have invented certain new and useful lmprovements in Adjusting Devices for Grinding- Wheels; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled'in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specicati'on 'This invention relates to a mechanism for .automatically adjusting grinding wheels an amount corresponding to their wear, and for,

automatically bringing such wheels into the proper position relatively to the blank. The

mechanism, constituting the present invention, is adapted to be used in a great many 'l cases and its actionis more accurate than any prior mechanism for the'same of which lam aware. l

Accordin 'to this invention, the surface of the blanl to be ground, or the 4working surface of the grinding wheel, and in some purpose,

cases both these surfaces, are controlled by a feeler lever, which actuates devices connected l to electric circuits.- These devices are adapted to close or open said electric circuits, y which act 1n such a manner upon electromagnetic coupling members of devices for adjusting the grinding wheels, or in sorne cases upon the blank, that controlling an adjustment of the grinding wheel, or a movement thereof into the proper position is effected by the position of the' controlling surface.

This invention will nowv be more particularly described with referenceto the accompanying drawings, which illustrate several constructional examples of the invention. ln these drawings l Figure 1 is a perspective view showing some parts in section of one embodiment of the invention, Fig. 2 isa similar view illustrating an embodiment of the invention, in which the feeler member bears upon the working surface of the grinding wheel; l

Fig. 3 is a perspective view of a third construction vaccording to this invention4 embodying in part some features ofthe construction shown in Fig. 1 and in part some features of the construction shown in lFig. 2, and

4 illustrates an arrangement according to this invention adapted to be used in connection with machines grinding both when the table carrying the blank is moved in one direction and when it is moved in the opposite direction.

In carrying the invention intoy eect and referring to F ig. l, l provide on a main standard 1 of a grinding machine, for instance a surface grinding machine, a vertical slide 7 adapted to be moved in vertical direction by means of a hand wheel 2, bevel gearing 3, e, screw spindle 5 and nut 6. v In the slide 7 is mounted a constantly revolving shaft 8 driven by worm gearing 9, 10, and a belt pulley 11. An electromagnet 12 is rigidly mounted on the shaft 8, and a sleeve 13, provided at its lower end with ratchet-teeth. 14;, and carryingat its upper end a pinion is loosely mounted thereon. Pinion 15 meshes with a second gear 16, which is rigidly mounted on a screw spindle 17. The latter engages with a nut 18 of the bracket V19, in i whichis journaled the grinding wheel spindie 20, carrying the grinding V wheel 21.

vThis wheel grinds the blank 28, held on the table 22', which isv reciprocated on ways as usual.

24 denotes a feeler lever, which is pivotally connected at 25 to the slide v7.i The right hand end of this feeler lever carries a small disk 26, T.v'hicl'i is constantly pressed against the ground surface 28 of the blank 23 by a strong spring 27. rlhe left hand end of lever 24: acts upon the right hand end of a contact lever 29 pivotally connected at 3G to the slide 7. The left hand end *of this lever 29. carries a contact piece 31 by means of'a connection, comprising two contact rings 35, mounted on the shaft 8, and the' windings of 'the' electromagnet 12.

lt will befseen, that when the ground surface 28 of the blank 28 is in a suficiently high position,` the contact piece 31 comes finto contact, with the small plate 33. At

this time the electric circuit is closedv and .the electro-magnet 12 energized, so that it attracts an iron lever 38 arranged opposite its pole 86 and pivoted on a pin 37, ixed to the body of the electromagnet 12, the front ico vas

all

ing 15, 16 andthe screw spindle 17 as soon as the lever 38 engages with. the teeth 14: of said sleeve 13, so that the bracket 19, carrying the grinding wheel 21, is gradually lowered, @wing to this, the grinding action of the wheel 21 upon thel blank 23 is immediately increased and the ground surface. 28.

comes to lie to a certain amount lower down, this amount corresponding to the sinking of the grinding wheel. Further, as the action. of the strong spring 2T overcomes the action of the weak spring 32, the small disk 23 of the feeler lever 2li isfalso moved downward to as corresponding amount, while on the other hand the contact piece 31 is moved away from the contact plate 33, 'llhe electric current dowing through the windings of the electromagnet 12 is now ini terrupted and the end 39 of lever 38, acted upon by the spring 34,-, is caused to disengage the teeth 1d of the sleeve`13. Hence,

the revolving movement of the sleeve 13 and the downward movement of the grinding wheel 21` are arrested. This occurs at the time, at which the contact between the pieces 31 and 33 is interrupted, that is, at a determinate distance of the ground surface 28 from the lower .edge of the slide 7,

Should it be necessary to grind od a further amount of the blank, the slide 7 is lowered toy a corresponding amount by means of hand wheel 2 and the screw spindle 5, while the blank 23 is on the right hand side out of reach of the grinding wheel 21. Upon a downward movement of the slide 7, the support 19 and the grinding wheel 21 are also caused to move in the same direction, During the immediately following movement of the table 22 'toward the left, the blank 23 is ground od to an amount, which corresponds to said downward movement of the. slide 7, so that the distance of the surface 28, just acted upon by the wheel 21, from the lower edge of the slide 7, is again exactly the same as before the grinding., rlhe grinding of the blank causes, however', a. continual wear of the grinding wheel, so that the parts of the ground surface 28, lying-farther to the right are left progressively higher than the left hand end of said surface, which has been acted upon by the grinding wheel at the beginning of the table movement. The smallest'elevation of the ground surface has, however, the

neeegves peated and alowering, that is, 'an adjustment of the grinding disk being edected.

This adjustment of the grinding disk causes in its turn a lowering of the ground surface, which .has the edect to induence the feeler lever 2d in such a manner, that the electric circuit is again interrupted at 33, so that` the adjustment of the grinding disk 21 is arrested. rlhe hereinbefore described -working cycle is repeated as many times during the progressive movement of the table 22 toward the left, as the wear of' the grinding diskv causes the contact piece 31 to come in contact with the Contact plate 33, so that the longitudinal prole of the ground surface of the.

blank, that'has been passed beneath the grind. ing wheel is undulated, the height of the undulations corresponding to the diderence between .the positions of the contact piece 31,'

at which the latter just closes the circuit and at which itis still able to just interrupt the circuit. rllhis amount is so exceedingly small, thatthe ground surface maybe regarded prac- 'tically as an even surface llnany case' said l ground surface of the blank, but by the working surface of the inding wheel, for instance the cylindrical surface of the wheel of a circular grinding machine. ln such a case the didicultyv arises, thatk the fee-ler memberv is actuated by a surface having a very great speed of rotation.- 'llhe first' condition, which has therefore to be fullled, is that the feeler member must be made of a material which is harder than the grinding wheel, Such a material is, for instance,

diamond. lt is, however, advisable, even when diamond is used and is provided with a ground surface, in order'to prevent a useless grinding effect of the grinding wheel, to

arrange that it does not touch the 'grinding' wheel longer than is absolutely necessary. ln a device constructed in the same manner as that shown in Fig. 1, the diamond would, however, constantly touch the grinding wheel, unless an adjustment is just taking place, so that the diamondwould also be in contact with the grinding wheel when the latter is running idle, in which casel no wear of said wheeltakes place and the diamond would thus be subjected to a gradual wear, which has to be prevented as far as'possible.

Hence, the device shown in yFig. v2 isconstructed in such a manner, that the -feeler member touches the worlnngigrinding surface only from time to time and. for a short Lasagne moment, said member serving upon a wear circuitl actuating a relay, which effects a rsmall adjustment of the grinding wheel. At

other times the feeler member does not touch the grinding Wheel, so that it is not affected by the latter. It will be seen from the following description, that the adjustment, corresponding to the amount of the whole wear, consists in a combination, generally speaking, of a number of single adjustments.

On the shaft 8, which is slowly driven by the pulley 11 and the worm gearing 9, 10, is mounted a sleeve 40 adapted to be moved in the axial direction of said shaft, and a loose sleevel 41 carrying at its upper end a bevel gear 42. The sleeve 40'is provided with clutch teeth 43 and an annular groove 44. A pin 45 projects normally into this groove and prevents the teeth 43 from engaging with the teeth 46 of the sleeve 41.v

, The pin 45 carries an adjustable collar 47 acted upon by a spring 48, which is arranged between this collar 47 and the bearing 49. The outer end of the pin 45 has a recess 50, into which projects normally al j locking lever 51. This lever 51 is pivotally mounted on a fixed pin 52 and is kept in its normal position by a spring 53. A collar 54, having a recess 55 in its periphery, is rigidly connected to the shaft 8. On this collar slides a projection 56 of the feeler lever 24, pivotally mounted on a fixed pin 25. One arm of this lever forms a contact lever and carries a contact piece 31, while the other arm is provided with a diamond 26 acting as a feeler. A spring 27 presses constantly'the lever 24 on the one hand againstlthe active surface of the grinding wheel 21 and on the other hand against the contact piece 33, so that the projection 56 rests constantly on the cylindrical periphery ofthe collar 54.

As soon as the recess 55 of the collar 54 passes, durin the movement of the shaft 8 beneath the pm 56 of the feeler lever 24, the latter is oscillated by the spring 27 both toward the grinding wheel 21 and toward the contact piece 33. lf it is assumed, that the contact piece 31 reaches the contact plate S3-before the feeler member 26 comes in contact with the grinding wheel, an electricv circuit is closed, so that an electric current ted to sleeve 40 and, by means of the bevel gearing 42, 58, also to the shaft 59. The latter carries at its outer end a disk 60, having an veccentrically mounted pin 61. This pin carries a pawl 62 engaging with a ratchet-wheel 63 and imparting to ,the latter a feeding movement upon each rotation of the shaft 59. This movement of the ratchet wheel 63 is transmitted to the screw spindle 64, rigidly connected to said Wheel,

and causes an adjustment of the support 19- of the grinding wheel spindle, and therefore of the grinding wheel 21, toward the feeler 26 of lever 24. i

When the clutch sleeve 40 has nearly completed one revolution, a pin 65, fixed to said sleeve is acted upon by a stationary, helical cam surface y66, so that said sleeve' 40 is moved longitudinally of the shaft 8, upon further rotation of the latter and is thereby disconnected from the clutch sleeve41. The rotation of the sleeve 41 and the adj ustrnent' of the grinding wheel 21 are then arrested. As soon as the clutch sleeve 40 is returned into its normal position, the rear end of the pin 45 is againV pushed into the annular groove 44 of the sleeve 40. This is effected by a cam surface 67 provided on the worm wheel 9 and acting upon a member 68 -rigidly connected to the pin v45. Upon the returning of the pin 45 into its normal-position, the locking lever 51 is again pressedinto the recess 5() by the spring 53, and prevents withdrawal of the bolt 45 from the annular groove of the sleeve 40, -after the cam 67 has been moved out of reach of the member 68, as the locking lever 51 is then only acted upon by said spring 53, the electromagnet 57 being no longer energized, since the circuit, closed by the contact piece 31v coming in contact with the plate 33, has been immediately interrupted after the recess 55 has been moved out of reach of the projection 56.

Shortly' after that the pin 45 has been locked, the recess 55 passes again beneath the projection 56 and the feeler lever 24 is again oscillated toward the contact piece 33 and the grinding wheel respectively. When the grinding wheel has not been moved so near tothe feeler member 26, during the v lpreceding adjustment, that the contact .piece 3l is prevented from touching the plate 33, the hereinbefore described working cycle is repeated and al second adjusting movement is imparted to the grinding wheel, the

- amount of this second movement corresponding to that of the iirst one.r This is repeated until an oscillation of the lever 24 finally brings the feeler member into contact with the grinding wheel 21 before the contact piece 3l is able to touch the contact plate 33. is not closed and the electromagnet 57 does not attract the locking lever 51, so that the ln this case the electric circuit pin t5 and the clutch sleeve 40 are not released. rlhus, the rotation of the shaft 8 is not transmitted to `the sleeve Ll1 and no ad justment of the grinding wheel takes place.- Should, however, anywear of the grinding wheel occur, the contact piece 31 is again' permitted to touch the contact plate 33 before the ieeler touchesthe grinding Wheel and as many small adjustments of said wheel are then again eiiected as necessary to compensate for the amount of the wear.

Also the sensitiveness of this device depende likewise upon the exceedingly small didcrence of the positions of the. contact piece 31, which are determinative for thev closing and the not closing, respectively, ci the electric circuit, since the amount of veach single adjustment may be made equal to the amount of said diderence. The'ratio of thisamount to 'the amount ot theempirical wear of the grinding wheel determinesmoreover the duration 'of the time interval between two successive adjustments and therefore also the number of rotations of the shaft 8. @wing to the very great sensitiveness of this adjusting device with regard to an incorrect position of the v active grinding surface, it is dicult to move the grinding wheel by hand at the beginning of the operation .exactly into the proper position. vln practice an approximation of about 1/16 mm. is the'closest, which can'be attained. 0n the other hand,l the amount of a single adjustment may be reduced to about 1/1000.

mm. and the time interval between two ad justmcnts may be extended over about. 6 seconds. of 'the active inding surface from itsl proper position, the adjusting device begins, of course, immediately to work. To traverse .said distance there are needed, however, if

it is assumed that a single adjustment is of the above mentioned amount, 100y adjustments, so that the whole adjustment lasts 600 seconds, that is 10 minutes, if -it is assumed that a single adjustment lasts 6 seconds. rlhis means an unnecessary loss of time, which is .eliminated in the device-illus.-

. trated in Fig. 3. l

- The device shown in 3 vis a' combination of the devices illustrated in Figs. 1 and s 2 and it is adapted to be used, :tor instance,

in combination with a machine for grinding toothed wheels having a tlat plate-like grmding wheel provided with a narrow circular rim. The part of the device corresponding to that shown in Fig. l serves tov move the grinding wheel quickly into its proper position at the beginning ci 'the' work or a wheels, while the part ot vthe device corresponding to that shown in Fig.. 2 serves to '-edect the adjustment ofthe grinding wheel in accordance with the'amount oi the rogressive wear taking place during the gund- At the above mentioned distancev iter an interchange of the grinding maneges ing process. 'Also in this case the provision ot a device corresponding to that shown in Fig. 2 an' eecting the work adjustment. during the grinding process, is rendered necessai-y,- owing to the circumstance,that the eeler member is not controlled by the blank,

but by the grinding wheel, so that, for thepurpose of preventing a rapid wear of the.A

eeler member, the same principles are determinative as stated with regard to the device shown in Fig. 2. i

The combin tion ot both arrangements requires the following modications of the mechanism instead of the collar 54 being rigidly connected' to the shaitt as in Fig. 2, in the arrangement shown in Fig. 3, the collar 5a is adaptedto be moved in the axial 'direc- `t-ionot said shaft. lhe hub 69 of said collar 5ft has an annular groove 70,in which engages a-hook 71, on'the end of a hand lever 72, the collar 515'; being adapted to be moved in such a manner in the axial direction ofthe shaft 8, by means of said lever 72, that the projection 56 ci the eeler lever 2t does Enot rest any longer on the cylindrical rim of the collar 54. Upon movenient of the collar 5d out of reach of the projection 56, thev eeler lever 24 is, however,

` oscillated towardl the grinding wheel, which it 1s prevented from touching owing to the corresponding magneti, in Fig. 1,.a lever 38,.

the iront end 39 of which engages in the same manner with the teeth of a ratchet wheel nlll. Owing to the actuation of the electromagnet 57 the clutch -sleeve l0 has been released, in the Same manneras in the device of Fig. 2, so that said sleeve engages' with the sleeve d1, causin .thereby la rotation of the shaft 59. Th' rotation of this yshaft is now transmitted by the electromagnet 12 and the lever 2:38l to the ratchet. wheel 14, loosely mounted on said shaftand to the small spur gear 15 rigidly connected to saidv wheel 1d. lhe gear 15 'engages in its turn withI a spur gear 16, rigidly connected. to the ratchet wheel 63. While .the electromagnet 12 vis energized, the revolving bevel gear l2 causes a much quicker adjuent of the' grinding wheel by means of the spur gears 15, 16, than that l caused b the pawl and the ratchet gear 62, 63. otation ofthe shaft 59 is stopped vas soon asthe vpin 65, acted uponby the helical surface 66, moves the sleeve 4Q out 13o of engagement with the sleeve 41, but it is restarted upon release of the member 68 from the cam 67, as the electromagnet 57 is still being energized, so that the pin 45 is not locked. The quick adjustment of the grinding wheel, by means of the members 12, 38, 14, 15, 16, occurs at short intervals until the active surface of the grinding wheel touches the feeler member. As soon this is the oase, the circuit is interrupted at 33 and the magnet 12 is rendered inoperative. The spring 34 then causes the lever 38 to disengage the ratchetwheel and the gearing 15, 16 is again arrested. Only the shaft 59 is further rotated until the sleeve 40 iscaused to disengage the sleeve 41. But, since the electromagnet 57 is also no longer operative, the lever 45 is locked immediately afterward, so that any adjusting movement of thegrinding wheel is interrupted. j

When the pawl 62 has been moved away from the wheel 63 before the starting of said quick adjustment, the rotation imparted to the shaft 59 for a short moment after` said quick adjustment has been effected, does not cause any further adjustment of the grinding wheel, so that the latter is moved exactly into its proper position owing to said quick adjustment. As soon as this is the case, the collar 54 is brought back within reach of the projection 56 of the feeler lever 24 by means of the hand lever 72, the inclined ysurface 73 on the'collar 54 causing said pin to ride up onto the cylindrical rim of said collar. At the same time the pawl 62 is moved back into its working position. Now when the grinding wheel begins to wear, this device works just in the same manner .pas that shown in'Fig. 2, since the electromagnet 12 has been disconnected from the electric circuit owing to the displacement imparted to the hand lever 72.

Both in Fig., 2 and in Fig. 3, it has been assumed, that the support for the grinding wheel and the whole adjusting device are mounted as in Fig. 1, on a common slide, which is adapted to be adjusted in any suitable manner by hand or by the machine itself, without said adjusting device being affected in any way. In this manner itis possible to determine the position of the active grinding wheel according to requirements, while the adjusting device is only operated by those displacements of the active grinding surface, which are due to the wear of the grinding wheel. To this end it is particularly advisable to provide a special slide for the support for the grinding wheel, which is adapted to be displaced relatively to the adjusting device. In this case the position. of the active grinding surface relatively to the adjusting apparatus is then -always determined by the position of the contact piece 33 on the one hand and the positions of the contact piece 314 and the feeler member 26 on the other hand.

Upon comparison of Fig. 1 on the one handjand Figs. 2 and 3 on the other hand it will be seen that, in Figs. 2 and 3, the feeler lever acts at the same -time as a contact lever, while in Fig.: 1 the feeler lever and the Contact. lever formtwo separate pieces. In this latter case I always prefer to provide two levers, as a single lever might easily be bent. Letvit beassumed, for instance, that the device of Fig. 1 comprises only the lever 24. In this case the contact piece 31 would have to be fixed to theleft hand end of this lever 24 in a downward direction and thecontact piece 33 would then have to lbe arranged opposite and below said piece 31. If an velevated work surface vshould now be moved under the f eeler lever, while the grinding wheel is also too much elevated, said lever could not bev oscillated and it would thus be bent. The feeler lever would also be prevented'from following the undulations of the ground surface, so that the progressively higher work surface would also cause a bending of said lever, as the latter would be already in contact with the 'small contact plate for the purpose of starting the adjustment of the grinding wheel, while the effect of the adjustment can'only influence the feeler,.when the work surface, ground again to the proper height, passes beneath the feeler member. This didiculty is overcome by providing two levers instead of only one, as the feeler lever 24 is then able to follow each rising of vthel grinding wheel, the left hand end of said lever being in this case even able to oscillate, when the contact lever29 is already prevented from oscillating byA the contact piece 31 resting on the small contact plate 33.

In the arrangements shown in Figs. 2v and 3, such a division of the lever in two single parts is not necessary, as the contact lever can never be bent when the grinding wheel is in a wrong position.

This difference in the arrangement of the feeler lever and the contact lever, due to the above mentioned reasons, in the two embodiments is, however, practically of no importance for the action of the feeler lever as a switch. llt is only essential, that the oscillation of the feeler lever be able to eiect a closing and opening of the electriccircuit,

it b'eingimmaterial, whether this isaccomtively. Of course, the devices shown in Figs. 2 and 3 may also be used in connection with surface grinding machines of the type shown in Fig. 1, that is, where the feeler lever is controlled by the blank and not by the grinding wheel, it being, however, understood, that in this'case the .arrangement of the feeler lever and contact lever would remain the same as in Fig. 1, owing to the above stated diliculties On the other hand, it would also be possible to use the device shown in Fig. 1 in connection with circular grinding machines and to control the feeler by the blank instead of by the grinding wheel. Also in this casev it-would be necessary to provide a separate feeler lever and contact lever respectively, as this division of the feeler and Contact lever into two parts is only necessary when the feeler is controlled by the blank, while when the v lgrinding wheel is the controlling agent, the

eeler lever and contact lever may be formed in one piece.

With regard to the device shown in Fig. 1, it has been assumed, that the blank is moved in such a direction relatively to the grinding wheel, that the` feele'r lever comes in contact with the surface, which has just been ground 'by the grinding wheel during the movement of the blank beneath said wheel. In other words, it has been ,assumed that the blank is moved relatively to the grinding wheel, and that the axis of the grinding spindle does not change its position. In this case the feeler lever is able to react when a wear of the grinding wheel takes place and to effect in the described manner a corresponding adjustment of the grinding wheel by means of the device shown in Fig. 1. The conditions are, however, quite dii'erent when lthe table 22 is moved in the opposite direction. The feeler lever is then moved a second time, but in the opposite direction, over the blank surface, which has been ground and -by which it hasbeen controlled during the previous travel of the table 22, and it is prevented from coming in contact with the surface, which is ground during this travel of the table. Owing to this, the device is not able to compensate the wear of the. grinding wheel taking place during the return travel by imparting a corresponding adjusting movement to said wheel. This lever may even cause entirely wrong adjustments, when the `feeler is not removed from the blank during the return travel of the table, or when the electric circuit is not 1interrupted. Thus, the device shown in Fig. lworks only in a proper manner for one direction of movement of the table, that is, for the direction assumed in the hereinbefore descriptable carrying the blank is moving in both directions, by the provision of a feeler lcver, and a contact lever respectively on each side of the grinding wheel 21.

Fig. 4 illustrates such a double arrangement of the levers and the modifications, which have to be applied in this case to an arrangement of the kind shown in Fig. 1.

The circuit of the electromagnet 12 comprises a control lever 78 acted upon by the dogs and 76 and pivotally mounted on the pin 77 and reversing the directionof movementof the table 22. In one end osition of this table 22 the control lever 78 is acted upon by the dog 76, so that its end 79 comes in contact With the small contact piece 80. The electric current, acting upon the electromagnet 12, flows therefore through the contact piece 31a of the contact lever 29a and the small contact plate 83a. Upon-a reversal of the control lever 78 the direction of movement of the table 22 is reversed also, so that the table is now moving in the directionof the arrow 81. The feeler lever 24a comes thus in contact with the surface, which is ground during this movement of the table 22, and as the corresponding contact lever 29a is connected to the electric circuit, the adjusting device is able to fulfil the task, which has been assigned to it, that is, to compensate the wear of the grinding wheel by 'means of a corresponding adjustment of said wheel. During this movement of the table 22 in the direction of the arrow 81, the feeler lever 24 and contact lever 29, which are arranged on the other side of the grinding wheel 21,- are not operatively connected to the adjusting device,.so that the movement of the eeler lever 24 does not influence the device.- In the other end position of the table 22 the control lever 78 is reversed by the dog 75, so that its end 79 comes to rest on the small contact piece 82. The current, energizing the electromagnet, flows then through the 110 contact piece 31 of the contact lever 29 and thesmall contact plate 33. The double lever 29, 24 is now electrically connected to the adjusting device, while the double lever 29, 24a'is disconnected therefrom. As also the 115 direction of movement of the table 22` has been reversed, so that it is moving in the vopposite direction to the arrow 81, the feeler lever 24, controllingnow the adjusting device, is able to come again in contact with the surface, which is ground during this movement of the table, and the device is thus able to effect, also forv this direction of movement of -the table, an adjustment corresponding to the wear of the grinding wheel. Of course, the levers of the two systems have to be set in such a manner, that both contact levers close the electric circuit, when their corresponding fceler levers come in contact with one and the same surface. This adjustment of the levers may be effected in a very simple manner by adjusting the contact pieces 31 and 3la respectively, they being formed in the shape of set-screws.

Thus, the device of Fig. l is rendered capable, by duplicating the lever arrangement and the electric connections according to Fig. 4, of adjusting thepgrinding Wheel in accordance with its wear for both directions of movement ot the table carrying the blank. V

Hereinbefore it has always been assumed, that the adjustment of thegrinding wheel is started upon the overcoming of a spring action by the pulling action generated at the moment in which the electric circuit is closed by the contact lever. Thearrangement may, however, be alsov such, that the adjustment is not effected by the closing of an electric circuit, but by the opening of such a circuit. In such a case, the spring and the electromagnet change their roles. Thus, in the arrangements shown for instance in Figs. Qfiand 3, the electromagnet 57 has to take the place of the spring 53 and fulfil the task of the latter, while on the other hand the spring 53 has to fulfil the function of the electromagnet 57. The pulling action of the electromagnet overcomes then the spring action at the time, during which the device is not operative, while this spring action overcomes said pulling action at the time, during which the adjustment of the grinding wheel is effected. Further, it is also only essential for these devices that the feeler lever act either directly, as in the device according to Figs. 2 and 3, or indirectly, as in the device according to F ig. l, as a switch in an electric circuit, which causes, upon its closing oropening, the adjustment of the grinding wheel.

Furthermore, it has hereinbefore always been assumed, that the adjustment of the grinding Wheel iseiiected upon the coupling of a constantly rotating shaft 8 to the clef ments which eii'ect the adjustment. This is, however, not essential, as the elements eiecting the adjustment might as Well be actuated by la small electromotor, which normally would not be running and which would only be set in motion upon the closing of the electric. circuit by the contact lever, suchmotor eecting thereby theadjustment either in one operation, as in the arrangement shown in Fig. Il, or in an intermittent manner, as in the arrangements shown in Figs. 2 and 3.

l1 or thev proper working of the device it is also not essential, that the compensation for the wear of the grinding wheel be effected by the adjustment of the grinding wheel, for said compensation might as well be e'ected by a corresponding adjustment of the Work. ln this case the whole device, comprising the feeler members, contact and adjusting-members, has only to be arranged on the table of themachine and not on the support for the grinding wheel. Such an arrangement lisfparticularly adapted to be applied to machines, in which also the ordinary feed movement is controlled by the blank, as the adjustingmembers may then act directly upon the feeding member, so that vno special slide, adapted to be moved relatively to the adjusting device, has to be provided,as it is the case in the arrangements shown in Figs. l to 3.

What l claim is;

. l. In a grinding machine, the combination with thework-support, the grindingwheel, and means for feeding one relative to the other, of means for automatically compensating for the wear of the grindingwheel, comprising a constantly driven shaft, a clutch to connect the same to said feeding means, and electro-mangetic means to control said clutch, the circuit of said electro-magnetic means including a feeler responsive to wear of said grinding-wheel.

2. In a grinding machine, the combination withthe work-support, the grindingwheel, and means for' feeding. one relative to the other, of means for automatically compensating for the'wear of the grindingwheel, comprising a constantly driven member, means to connect the same to said feed-- lng means, a feeler, the position of which is determined by the wear of the grindingwheel, and means, controlled by said feeler, to render said connecting means operative Whenever the grinding-wheel has worn a certain amount.

3. Tn a grinding machine, the combination with the work-support, theV grindingwheel, and means for feeding one relative to the other, of means for automatically compensating for the wear of the grindingwheel, comprising a'feeler lever, the. position of which is determined by the wear of the grinding-wheel, an electric circuit arranged to beopened or closed by said feeler lever, a source of power, a clutch t0 connect the latter to said 'feeding means, an

electromagnet in said circuit controlling the operation of said clutch, and means to disengage said clutch when Said circuit is opened.

4. Iny a grinding machine, the combination with the` work-support, the grindingwheel, and means for feeding one relative to the other, of means for automaticallyv compensating for the wear of the grindingwheel, comprising a feeler lever, the position of which is determined by the ywear of the grinding-wheel, an electric circuit arranged to be opened and closed by said feeler lever, a constantly rotating member arranged to oscillate said lever at regular intervals, means, controlled by said circuit to intermittently connect said member to said feeding means, and means, also controlled bysaid circuit, to connect said member to said feeding means to, impart a relatively lrapid and greater feeding movement between the grinding-Wheel and Work.

5. In a grinding machine, the combination with the Work-support, the grinding- Wheel, and means for feeding one relative to the other, of means forv automatically compensating for the Wear of the grinding-l Wheel, comprising a, feeler lever, the position of which is determined'by the Wear of the grinding-Wheel, an electric circuit arranged to be opened and closed by said feeler lever, a constantly rotating member arranged to oscillate Said lever at regular intervals, means, controlled by said circuit to intermittently connect said member to said feeding means, means, also controlled by said circuit, to connect said member to said feedingmeans to impart a relatively rapid and greaterv feeding movement between' the grinding-Wheel 4and Work, and manuallyoperable means to move said rotating member so that it no longer oscillates said lever, said `manuallyoperable means at the same time affecting said circuit so as to render operative the said means for imparting the 'rapid feeding movement.

'6l A feeler member adapted to be` used in devices for automatically compensating the Wear of 'grindingwheels occurring during the grinding operation, comprising a diamond having a ground fiat surface, substantially as described.

IIn testimony that I claim the foregoing as my invention, vI have signed my name in presence of two subscribing Witnesses. MAX MAAG. Witnesses:

CARL CUERIER, ARNOLD LEHNER. 

